J/A+A/686/A249 CI Tau light and radial velocity curves (Manick+, 2024)
Long-period modulation of the classical T Tauri star CI Tau.
Evidence for an eccentric close-in massive planet at 0.17 au.
Manick R., Sousa A.P., Bouvier J., Almenara J.M., Rebull L., Bayo A.,
Carmona A., Martioli E., Venuti L., Pantolmos G., Kospal A., Zanni C.,
Bonfils X., Moutou C., Delfosse X., SLS consortium
<Astron. Astrophys. 686, A249 (2024)>
=2024A&A...686A.249M 2024A&A...686A.249M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Stars, variable ; Photometry ;
Optical ; Radial velocities
Keywords: techniques: radial velocities - planets and satellites: detection -
planet-star interactions - stars: activity - starspots -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
Detecting planets within protoplanetary disks around young stars is
essential for understanding planet formation and evolution.
However, planet detection using the radial velocity method faces
challenges due to the strong stellar activity in these early stages.
We detect long-term periodicities in photometric and spectroscopic
time series of the classical T Tauri star (CTTS) CI Tau, and retrieve
evidence for inner embedded planets in its disk.
The study conducted photometric and spectroscopic analyses using K2
and Las Cumbres Observatory Global Network light curves, and
high-resolution spectra from ESPaDOnS and SPIRou. We focused our
radial velocity analysis on a wavelength domain less affected by spot
activity. To account for spot effects, a quasi-periodic Gaussian
process model was applied to K2 light curve, ESPaDOnS, and SPIRou
radial velocity data. Additionally, a detailed bisector analysis on
cross-correlation functions was carried out to understand the cause of
long-term periodicity.
We detect coherent periods at ∼6.6d, 9d, ∼11.5d, ∼14.2d, and ∼25.2d,
the last of which is seen consistently across all datasets. Bisector
analysis of the cross-correlation functions provides strong hints for
combined activity-induced and Doppler reflex signals in the radial
velocities at a period of 25.2d. Our analysis suggests that this
periodicity is best explained by the presence of a 3.6±0.3MJup
eccentric (e∼0.58) planet at a semi-major axis of 0.17au.
We report the detection of a massive inner planet in CI Tau. Our study
outlines the difficulty of searching for disk embedded planets in the
inner 0.1 au of young and active systems. When searching for planets
in actively accreting stars such as CI Tau, we demonstrate that the
primary limitation is stellar activity rather than the precision of RV
measurements provided by the instrument.
Description:
In this paper, we report the detection of a significant periodic
signal at ∼25.2d in both photometric (K2 and LCOGT) and
spectroscopic time series (ESPaDOnS and SPIRou RVs).
Photometric time series data for CI Tau were obtained
at Las Cumbres Observatory Global Network (LCOGT) within two epochs
separated by two years apart. The first epoch (20B) covered from
October 30, 2020 to January 31, 2021 (JD 2459153 - JD2 459245)
where 539 images were acquired in the Sloan g'r'i' filters over three
months with a sub-day sampling rate (runs LCO2020B-019, P.I. L.
Rebull; CLN2020B-005, P.I. A. Bayo, for a total of 11 hours). The
second epoch (22B/23A) extended from September 27, 2022, to March 31,
2023 (JD 2459850 - JD 2460033), during which 564 images were
acquired over six months in the Sloan g'r'i' filters, with a sampling
of typically one measurement per day (runs DDT2022B-003, DDT2023A-001;
PI L. Rebull, for a total of 11 hours).
Spectroscopic observations were conducted using the ESPaDOnS
spectropolarimeter at the 3.6m Canada-France-Hawaii Telescope (CFHT)
on Mauna Kea, Hawaii (PI: J. F. Donati). A total of 72 spectra were
obtained over a time span of ∼ two months, from mid-December 2016 to
mid-February 2017.
425 SPIRou spectra (four sub-exposures per night) were obtained for
CI Tau during five semesters ranging from 18 December 2018 to 13
January 2023 (PI: Jean-Francois Donati), covering a total time span
of ∼1487 days, but with significant gaps in the RV time series and a
varying number of RV points among semesters.
Objects:
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RA (2000) DE Designation(s)
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04 33 52.01 +22 50 30.0 CI Tau = EPIC 247584113
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
20b-g.dat 51 156 LCOGT light curve in g band (31/12/2020-08/01/2021)
20b-r.dat 51 164 LCOGT light curve in r band (31/12/2020-08/01/2021)
20b-i.dat 51 164 LCOGT light curve in i band (31/12/2020-08/01/2021)
22b23a-g.dat 51 165 LCOGT light curve in g band (27/09/2022-31/03/2023)
22b23a-r.dat 51 172 LCOGT light curve in r band (27/09/2022-31/03/2023)
22b23a-i.dat 51 175 LCOGT light curve in i band (27/09/2022-31/03/2023)
rvs.dat 101 493 ESPaDOnS and SPIRou radial velocities
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Byte-by-byte Description of file: 20b-[gri].dat 22b23a-[gri].dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 d JD Julian date
26- 49 E24.18 mag mag Magnitude in Band
51 A1 --- Band [gri] Observed band
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Byte-by-byte Description of file: rvs.dat
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Bytes Format Units Label Explanations
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1- 24 E24.19 d MJD Modified Julian date
26- 50 E25.19 km/s RV1 Original radial velocities obtained from
ESPaDOnS LSD profiles and SPIRou CO CCFs
52- 76 E25.19 km/s RV2 Radial velocities after removing a Gaussian
process spot model with a 9-day period from
the original radial velocities
78-101 E24.19 km/s e_RV Radial velocity error
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Acknowledgements:
Rajeev Manick, rajeevmnck(at)gmail.com
(End) Patricia Vannier [CDS] 31-May-2024